This investigation will study the polyribosomes and protein synthesis in the livers of rats ingesting chemical carcinogens, ethionine, N-2-fluorenylacentamide, and 3'-methyl-dimethyl-aminoazobenzene and in hepatomas (primary and transplantable) and compared with that in normal livers. The response of polyribosomes to the administration of acute toxic agents such as ethionine and others, will be studied. Sucrose density gradients of polyribosomes (total, free and membrane-bound) of livers and of hepatomas as well as protein synthesis will be measured. Studies will be conducted to determine whether the altered or adaptive response of polyribosomes of livers during chemical carcinogenesis and also of hepatomas to the acute administration of toxic or carcinogenic agents may be related to carcinogenesis. BIBLIOGRAPHIC REFERENCES: Murty, C. N., Verney, E., and Sidransky, H. Initiation factors in protein synthesis of liver and skeletal muscle of rats force-fed a threonine-devoid diet. Proc. Soc. Exp. Biol. Med. 145:74-79, 1974. Murty, C. N., Verney, E., and Sidransky, H. Initiation factors in protein synthesis by free and membrane-bound polyribosomes of liver and hepatoma. Biochem. J. 152:143-151, 1975.